1. Field of the Invention
The present invention relates to a clean booth and a sheet conveyor device which are suitable for feeding recording sheets, and more particularly to a clean booth and a sheet conveyor device that are able to decrease the amount of dust near the recording sheets.
2. Description Related to the Prior Art
In manufacturing sheet products, such as photosensitive recording sheet products, a recording sheet web is pulled out of a recording sheet roll, and is cut to form plural recording sheets of a certain length. The recording sheets are conveyed to a collection unit in which several recording sheets are bunched. Then, a bunch of the recording sheets is covered with a protection cover and a light-shielding film.
In the above manufacturing process, conveyor belts come in contact with the recording sheets during conveyance, so the recording surface of the recording sheet is damaged by poor quality conveyor belt. Thus, the conveyor belt is required to be made of a material with low dust emission to protect the recording sheet from dust, and with sufficient flexibility to prevent pressure marks or flaw on the recording surface of the recording sheet.
As for the material for the conveyor belt, JP-A 10-39485 discloses a conveyor belt in which flexible fiber is transplanted so as to increase flexibility on the conveyance side. Because of much emission of dust, however, transplanted fiber is not suitable for conveyance of photosensitive recording sheets. In order to accomplish low dust emission, U.S. Pat. No. 5,895,138 (corresponding to JP-A 9-325465) describes a conveyor belt covered with a material such as urethane. The conveyor belt of urethane, however, does not have sufficient flexibility to prevent pressure marks or flaw on the recording sheet.
In the sheet product manufacturing line, there are dust sources other than the conveyor belt. For instance, a motor drive mechanism is provided to operate a sheet cutter, a sheet conveyor, a sheet collector and so forth. The motor drive mechanism is composed of mechanical parts such as transmission belts, pulleys and gears. These mechanical parts rubbed with each other to generate dust, which causes deterioration in the quality of the recording sheets.
In order to remove dust in the manufacturing line, JP-A 5-18576 describes a clean room in which high-pressurized clean air blows downward through fan filter units in the ceiling. Clean air is blown outside together with dust through plural holes in the floor. However, the motor drive mechanism and the conveyor mechanism are provided in the same clean room. High-pressure clean air from the ceiling blows and flies dust onto the mechanical parts and the conveyor belt at the same time. Thus, the recording sheet is easily damaged by dust generated from the mechanical parts of the motor drive mechanism.